This invention relates to a data transfer system and more particularly to a system for sending signals from a plurality of sources over a common channel by serially sampling said source signals. This invention is particularly suited for sending signals from sonar trainer hardware to a remote sonar receiver for the purpose of simulating a plurality of transducer signals. In a serially sampled analog system, as in this invention, the pieces of information that must be transferred are the analog samples themselves, clocking information for the receiver sample and hold circuits, and synchronization information to identify the correct channel.
The traditional method of transmitting sampled analog data is to send the sampled analog data and the clocking/sampling information separately. When the timing skew of the driving circuits, the transmission medium, and the receiver circuits are considered, the timing skew soon becomes the dominant design factor and limits the data rate to about 1 Megahertz. For sampling rates higher than this, the clocking information and analog sampled data must, as in this invention, be encoded to follow the same transmission path thereby eliminating the skew problem.